Process of desulfurizing petroleum-oil.



T. MG GOWAN.

PROCESS OF DESULFUBIZING PETROLEUM OIL.

A iimion filed m 25, 1899.)

No. 658,857. Patented Oct. 2, I900.

(No Model.)

Iii/816 0 A6 71 0' I A ms MG (imu/ v Z3. I 1 3a W gash-2m THE nonmsPETERS co PROM-LYING" wnsumurun. n. c.

UNITED STATES PATENT OEEIcE.

THOMSON MOGOWAN, OF CLEVELAND, OHIO.

PROCESS OF DESULFURIZING PETROLEUM-OIL.

SPECIFICATION forming part of Letters Patent No. 658,857, dated October2, 1900.

Application filed May 25, 1899. Serial No. 718,277. (No specimens.)

To all whom it may concern Be it known that I, THOMSON MoGoWAN, acitizen of the United States, residing at Cleveland, in the county ofOuyahoga and State of Ohio, have invented a certain new and usefulImprovement in Processes for Desulfurizing Petroleum-Oil,of which thefollowingis a full, clear, and exact description, reference being had tothe accompanying drawing.

The petroleum-oils which are found in the Trenton rock and are commonlyknown as Ohio oils or Lima oils contain sulfur in combinations, whichmake its removal difficult. Nevertheless it is essential that it shallbe substantially eliminated at some stage in the treatment of the oiland before the refined products are marketable. The processes which haveheretofore been employed to produce this result have been objectionablemainly because of the large expense incident thereto.

My invention relates to a process for desulfurizing such oils, and itproduces the desired results with greater completeness and at less costthan any of the processes heretofore employed.

The process consists in an admixture with the sulfurized oil prior to adistillation thereof of concentrated sulfuric acid and in thendistilling the mixture of oil and acid, whereby a desulfurizeddistillate is obtained.

It also consists in the specific method of practicing the processhereinafter fully describedthat is to say, in adding to the crudesulfurized oil the concentrated sulfuric acid, in settling andseparating out the resulting precipitate or sludge and as much of theacid as will settle, and in subsequently distilling the remaining oiland so much of the acid as is held in suspension therein in the usualway. The sulfuric'acid is added to the sulfurized oil and thoroughlymixed with it.

The acid and the precipitate are allowed to settle and are drawn off,and the remaining oil, which contains some of the acid in suspension andwhich has been chemically affected by the acid in that the chemicalcompounds of sulfur have been rendered very unstable, is then distilledin the usual way, and substantially all of the sulfur passes off in agas during the distillation.

In stating that the acid is added before a distillation of the oil I donot mean that the oil may not be distilled before the acid is added; butI do mean that a distillation after the addition of the acid and whilesome of the acid-is held in suspension is an essential part of theprocess of desulfurization. It is preferable in the practical working ofthe process that the acid should not be added during the distillationand also that the oil shall not be distilled until after as much of theacid as will settle has been allowed to settle and it and theprecipitated matter have been drawn off.

The drawing shows an apparatus wherewith crude petroleum-oil may berefined and desulfurized according to my invention.

Referring'to the parts by letters, A represents a vessel or tank intowhich the oil to be desulfurized is placed. This tank may be oflead-lined metal or of any other suitable material. so shaped that anyprecipitated matter may be easily removed. Into this tank concentratedsulfuric acid is delivered and thoroughly mixed with the oil. Thequantity of acid which should be used depends upon the percentage ofsulfur in the oil as determined by analysis. For oil containing aboutsixtenths of one per cent. of sulfur the best results are attained, as Ibelieve, by using six thousand pounds of acid to fifty thousand gallonsof the oil.

The thorough mixing of the oil and acid may be effected by any suitablemeansas, for example, the air-agitator shown in the drawing. A pluralityof perforated pipes b is arranged in the bottom of the tank and isconnected with a supply-pipe I), through which air is blown byappropriate mechanism. After the thorough mixing of the acid and oil theacid is allowed to settle. It will carry down with it a very darkprecipitate or sludge containing a large proportion ofcarbonaceous'matter, which indicates that the oil has undergone achemical change in the loss of some of its carbon.

A discharge-pipe G is connected with the bottom of the tank, and it hastwo branches 0 a, each of which is provided with a stopcock c The acidand sludge are drawn ofi through the branch 0 into a suitable tank L,from which the acid is separated from the It has a conical bottom or abottom sludge and is recovered. This sludge after the acid has beenremoved is a valuable byproduct useful for making paving material and aninsulating material. The oil remaining in the tank A is then drawn offthrough the branch pipe 0. It may pass directly to a retort D or othervessel suitable for distilling it, or it may pass first to astorage-tank (not shown) and thence to the retort. The (listillation ofthe oil is, however, the next step in the process, and this may becarried on by the usual methods-that is to say, it may be evaporated,condensed, and preserved by means of ordinary and wellknownappliancesas, for example, the furnace (Z', retort D, worm d, and tank IThe percentage of distillate obtained should be governed by the desiredfinal results according to well-understood principles.

The mixture of the sulfuric acid with the oil prior to the distillationeffects such a change in the sulfur compounds in the oil that they arevery unstable. The result is that during the distillation which followsa Very large percentage of the sulfur is elimi' nated and passes otf inthe form of sulfurousacid gas. A stand-pipe N may be connected with thelower part of the worm-pipe, and through this stand-pipe this gas willpass. It may be recovered and then treated in the usual manner and isanother valuable byproduct of the process. The described processproduces an oil which contains less sulfur than does oil which has beentreated by any other desulfurizing process and at a very much reducedcost.

The subsequent treatment of the oil is dependent upon the final resultsdesired. The oil from tank F may be delivered into an agitator-tank G,having a conical bottom and a branched discharge-pipe g, the branches 9'and g having suitable stop-cocks 9 A solution of plumbate of soda isadded to the oil and thoroughly mixed with it by suitable means, as theair-agitator H, which is substantially like that shown in tank A andheretofore described. After this solution and the resultant precipitateshave settled they are drawn off through branch pipe g and delivered intoa receptacle I. The remaining oil is drawn off through the branch pipe 9and delivered either directly or indirectly to a retort J and againheated and fractionallydistilled. This fractionation is best secured bya column K, connected with the retort and having a height and diameterproportioned to the retort and suitable for securing the desiredresults. It has a plurality of enlargements is to'increase thecondensing-stirfaces and corresponding delivery-pipes k. The severalfractions may be collected in separate tanks as desired. The usualmethods of purification by means of concentrated sulfuric acid, water,and alkali are finally employed.

All of the process described which follows the first distillation isoptional and subject to variation. The process in so far as it includesmy invention does not necessarily go beyond the first distillation. Itincludes the mixture of concentrated sulfuric acid with the sulfurizedoil in withdrawing the acid and precipitated foreign matter and indistilling the remaining resultant oil. The product of the firstdistillation is preferably purified by the plutnbate-of-soda solution,and with some oils this or some equivalent treatment is essential. Itis, however, a well-known treatment in this art for securing certainwellknown results, and it produces those results more effectively withoil which has been previously treated with the sulfuric acid and thendistilled than with oil that has not been so treated; but there are oilswhich after being desulfurlzed as described do not require treatmentwith the plumbate of soda.

The various steps which follow the desulfurization of the oil by themeans described are illustrated and described for the purpose of showingthat my desulfurizing process may be a part of the ordinary process forrefining oils and that it adds very little to the cost of the refiningprocess either for the apparatus or material or labor.

Having described my invention, I claim- 1. The process of desulfnrizingcrude Lima or like sulfurized petroleum oil, which consists indistilling a mixture of sulfuric acid with said sulfurized oil which hasnot been previously treated so as to change the chemical character ofthe sulfur com pounds therein, substantially as specified.

2. The process of d'esulfurizing crude Lima or like sulfurized petroleumoil, which consists in agitating sulfuric acid with said oil; thenallowing the mixture to settle; then segregating the oil from theprecipitated sludge and so much of the acid as settles with it; andfinally distilling the said sulfurized oil with so much of the acid asremains mixed with it, substantially as specified.

In testimony whereof I hereunto affix my signature in the presence oftwo witnesses.

THOMSON MCGOWAN.

Witnesses:

E. L. THURSTON, PHILIP E. KNOWLTON.

